JPS6098525A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve dispersibility and magnetic characteristics of magnetic powder by incorporating an org. dye compd. having 1 or <=2 acidic groups or the salts thereof into a magnetic layer. CONSTITUTION:The acidic group refers to a hydroxyl group, carboxyl group, sulfonic acid group, etc. The org. dye compd. that can have these acidic groups is an azo compd., etc. The org. dye compd. has a substituent except the acidic group and the acid group may form a salt by a metal or org. amine, etc. The magnetic paint obtd. by using the org. dye compd. and kneading and dispersing magnetic powder and binder by using an org. solvent, etc. is excellent dispersion stability and a low viscosity. The paint decrease varinish sepn. with age, is easily dispersible again and has excellent workability for coating.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording medium using magnetic powder and a binder, and particularly to a magnetic recording medium in which the dispersibility and magnetic properties of the magnetic powder are improved.

Conventionally, magnetic recording media such as audio tapes, video tapes, magnetic disks, and floppy disks have been prepared on supports such as polyethylene terephthalate, polyethylene naphthalate, cellulose triacetate, polycarbonate, polypropylene, polyvinyl chloride, aluminum, and alloys. To.

7-Fez03. Fe704L, cobalt-doped γ-Fez03. Magnetic powders such as CrO2, iron powders, and iron-cobalt nitride alloys are combined with vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinylidene chloride copolymers,
Butyl acrylate, butyl acrylate-acrylonitrile copolymer, cellulose resin, epoxy resin,
It was applied by kneading it with a binder such as polyurethane resin.

However, even when using these binders alone or in combination of two or more, the dispersibility of magnetic powder in these binders is poor, resulting in insufficient smoothness and stability of the two surfaces. In terms of characteristics, the squareness ratio (Br/8m)
, S/N ratio, sensitivity, etc. were very low.

For this reason, various additives are used for the purpose of improving the dispersibility, stability, etc. of magnetic powder.

For example, higher fatty acids, fatty acid amides, fatty acid esters,
These include quaternary alcohol ester, polyethylene oxide, lecithin, etc.

However, even with the addition of these additives, it has been difficult to obtain a magnetic layer having desirable characteristics. For example, when a large amount of these additives is used, surface smoothness and running stability are improved to some extent, but the mechanical strength of the magnetic layer decreases or the additives seep out onto the surface of the magnetic layer. A so-called blooming phenomenon occurs.

This gives undesirable results as a magnetic recording medium. In this way, the properties and dispersion of the magnetic layer as well.

It was by no means satisfactory.

The inventors of the present invention have made intensive studies to improve these drawbacks, and as a result, they have come up with the present invention.

That is, the present invention provides a magnetic recording medium in which a magnetic layer containing magnetic powder and a binder is formed on a support, wherein the magnetic layer contains an organic dye compound having one or more acidic groups or salts thereof. The present invention relates to a magnetic recording medium containing the following.

In the organic dye compound having an acidic group used in the present invention, the acidic group is a hydroxyl group, a carboxyl group, a sulfonic acid group, etc., and the organic dye compound that can have these acidic groups is an azo compound 2, for example, β −Naphthol series, β
- Oxynaphthoic acid series, β-oxynaphthoic acid arylide series, acetoacetic acid allylide series, acetoacetic acid aminobenzimidacylon series, pyrazolone series or fused azo series, fused polycyclic compounds 9 For example, phthalocyanine series, quinacridone series, anthraquinone series , perylene series, perinone series, thioindigo series.

Dioxazine series, isoindolinone series, quinophthalone series or triphenylmethane series, metal complex compounds, such as azo series, nitroso series and azomethine series, and these compounds remain as ligands that do not form complexes with metals. But it's okay. Alternatively, dyeing may be done using a lake compound 2, such as an acidic dye lake system or a basic dye lake system. The acidic group is directly bonded to the organic dye compound, or is an optionally substituted saturated or unsaturated alkylene group having 1 to 20 carbon atoms, with or without a carboxylic acid amide or sulfonic acid amide. They may be bonded via an arylene group.

In addition to the acidic group, the organic dye compound of the present invention has a saturated or unsaturated alkyl group having 1 to 20 carbon atoms, an aryol group, a halogen atom, and -OR+.

-N RIR,,--CON R,RS,-3O2N
R, Rz, SR,, --CN, -N Oyu,
NR+CORz, -NR,SO,R2,COOR3(
RI, R2 has a substituent such as a hydrogen atom, a saturated or unsaturated alkyl group having 1 to 20 carbon atoms, an aryl group, and RJ represents a saturated or unsaturated alkyl group having 1 to 20 carbon atoms. Also good.

Further, the acidic group may form a salt with a monovalent or divalent metal, an organic amine, or the like. In some cases, it may be an ammonium salt. The metal in the metal salt is sodium.

Potassium, magnesium, calcium, zinc.

barium, strontium, manganese, iron, nickel,
Cobalt etc. The amine of the amine salt may be an aliphatic primary amine, a secondary amine or a diamine.

In order to incorporate the compound of the present invention into the magnetic layer of a magnetic recording medium, at least one of the organic dye compounds according to the present invention may be incorporated.
The treated magnetic powder is obtained by dissolving the seeds in water or an organic solvent such as toluene, methyl ethyl ketone, or cyclohexanone, immersing magnetic powder in the solution at a predetermined ratio, stirring and mixing, filtering and drying. The powder and the binder may be kneaded, or at least one organic dye compound according to the present invention may be added directly or dissolved in a suitable solvent during dispersion of the magnetic powder. Furthermore, it is also possible to add the magnetic coating material before applying it to the support.

The organic dye compound of the present invention is usually 0.2 to 0.2 to the magnetic powder.
1% to 20% by weight, preferably 0.5% to 10% by weight
It is desirable to use it within a range of % by weight.

A magnetic paint obtained by cross-dispersing magnetic powder and a binder using an organic solvent or the like using the organic dye compound of the present invention is 1
It has excellent dispersion stability, low viscosity, and less varnish separation over time.

Again, the dispersibility is easy, and the workability of coating is also extremely excellent.

Fe30q doped with chromium dioxide, barium ferrite, or metal magnetic materials such as iron and cobalt, or various alloy magnetic materials such as Fe-Go, Go-
Ni, Fe-Co-Ni, N1-Co-B Fe-
Go-Cr, Fe-Cr-Ni, MoB1, etc.).

There are no particular restrictions on the binder that can be used in the present invention, and examples include vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, and polybutyl acrylate as described above.

Butyl acrylate-acrylonitrile copolymer, cellulose resin, epoxy resin, polyurethane resin, etc.
Various known binders and mixtures thereof can be used. In addition.

The binder may be of any type, such as a thermoplastic type, a thermosetting type, or an electron beam curing type.

In addition, in the present invention, 2 the organic dye compound of the present invention and 3 conventionally known dispersants such as lecithin, oxyamine compounds, alkylamine cationic surfactants, polyalkylene sorbitan alkylates, phosphate esters, or other lubricants. It is possible to further improve the characteristics of the magnetic layer by adding , a stabilizer, etc. in combination.

The magnetic recording medium according to the present invention includes magnetic powder,
A magnetic layer is formed by applying and drying a magnetic paint in which a binder and an organic dye compound according to the present invention are cross-dispersed using an organic solvent or the like. Conventional methods may be used to manufacture and apply such magnetic paints, and additives such as dispersants, lubricants, abrasives, antistatic agents, etc. may be added to the magnetic layer of the present invention as necessary. It may also be contained.

The support used in the magnetic recording medium according to the present invention is polyethylene terephthalate.

Any material such as polyethylene naphthalate, cellulose triacetate, polycarbonate, polypropylene, polyvinyl chloride, aluminum alloy, etc. can be mentioned.

Note that the magnetic layer of the present invention may be coated so as to have a dry film thickness of usually 2 to 20 microns.

The above description of the present invention has focused on the differences from conventional magnetic recording media, but there are other technical configurations as well.
For example, the type and amount of the binder and additives used as necessary, the type of support, the surface smoothing treatment method, the method of orienting the magnetic powder, the type of organic solvent used during coating, and the drying method. As for the curing method, etc., known techniques may be applied.

The present invention will be specifically described below with reference to Examples and Comparative Examples.

Example 1 γ-Fe doped with cobalt. Powder 100 parts by weight Vinyl chloride-vinyl acetate copolymer 7 Urethane elastomer 15 The following organic dye compound CI) according to the present invention 3 Toluene 50 Methyl ethyl ketone 50 Cyclohexanone 20 The above composition was mixed for 4 hours using a sand mill. A magnetic paint was obtained by dispersing it. This is referred to as paint 1-A. This paint 1-
After coating A on a 15 micron polyester film and drying it, the magnetic layer was surface treated using a super calendar roll and cured by heating. This is 3.81 cmdl
Examples 2 to 29 In place of the organic dye compound (1) according to the present invention used in Example 1, organic dye compounds shown in Table 1 below were used. Other compositions, operations, methods, etc. are the same as in Example 1. The thus obtained magnetic paints and magnetic tapes were used as paints 2-A to 29-A and samples 2-B to 2, respectively.
9-B.

Comparative Examples 1 to 3 In Example 1, one organic dye compound according to the present invention (1
) as shown in Table 2, Comparative Examples 1 to 3, respectively.
And so.

The characteristics of each of the magnetic paints of Examples 1 to 29 and Comparative Examples 1 to 3 and the characteristics of each sample of magnetic tape were measured, and the results are shown in Tables 3 and 4.

Table 1: Various organic compounds 2: Comparative additives 3: Characteristics of each magnetic paint (no varnish separation at all after 05 days) (varnish separation after 05 days without handling) (varnish separation after 2 days) (× Varnish separated immediately after dispersion) Magnetic alloy (Fe-Go-Ni) 100 parts by weight Polyester 6 "Uretashielastomer-16" Organic dye compound of Example 21 5 Toluene 20 Methyl ethyl ketone 80 Cyclohexanone 10 Above composition A magnetic paint was obtained by cross-dispersing the material in the same manner as in Example 1. This was referred to as paint 30-A. Further, this magnetic paint was treated in the same manner as in Example 1 to create a magnetic tape. is designated as sample 30-A.

Examples 31 to 58 In Example 30, organic dye compounds shown in Table 5 below were used in place of the organic dye compounds used.

Other compositions were the same as in Example 30, and a magnetic tape was prepared using the same operations and methods as in Example 1. Each of the magnetic paints obtained in this way was used as paint 31.
-A~58-A.

Further, the magnetic tapes are designated as samples 31-B to 58-B, respectively.

Comparative Examples 4 to 6 Comparative Examples 4 to 6 were prepared by replacing the organic dye compounds used in Example 30 as shown in Table 6.

The characteristics of each of the magnetic paints of Examples 30 to 58 and Comparative Examples 4 to 6 and the characteristics of each sample of magnetic tape were measured, and the results are shown in Tables 7 and 8.

Example 59 Cobalt-doped FeO powder 100 parts by weight Nitrocellulose resin 2 Urethane elastomer 16 Epoxy resin 4 The following organic dye compound (n) according to the present invention 5 Toluene 45 Methyl ethyl ketone 45 Cyclohexanone 20 〃 After cross-dispersing the above composition in the same manner as in Example 1,
3 parts by weight of polyisocyanate was added and mixed with stirring to obtain a magnetic paint. This is referred to as paint 59-A. moreover,
This magnetic paint was treated in the same manner as in Example 1 to produce a magnetic tape. This is designated as sample 59-B.

Examples 60 to 73 In place of the organic dye compound (If) according to the present invention used in Example 59, organic dye compounds shown in Table 9 below were used.

The other compositions are the same as in Example 59. After cross-dispersing this composition in the same manner as in Example 1, 3 parts by weight of polyisocyanate were added.

A magnetic paint was obtained by stirring and mixing. Paint 600 each
-A to 73-A. Further, this magnetic paint was treated in the same manner as in Example 1 to produce a magnetic tape. These are designated as samples 60-B to 73-B, respectively.

Comparative Examples 7 to 9 In Example 59, 9 organic dye compounds according to the present invention (
Comparative Example 7 by replacing If) as shown in Table 10.
~9 and sita.

The characteristics of each of the magnetic paints of Examples 59 to 73 and Comparative Examples 7 to 9 and the characteristics of each sample of magnetic tape were measured, and the results are shown in Tables 11 and 12.

Table 9 Table 10 Table 12 Examples 74 to 76 In Example 1, in place of the organic dye compound (1) according to the present invention used, 2 as shown in Table 13 (conventionally known dispersant and 2 organic pigments according to the present invention) were used. Compounds were added in combination. Other compositions, operations.

The method and the like are the same as in Example 1. The magnetic tapes thus obtained are designated as samples 74-B to 76-B, respectively.

The characteristics of each sample of the magnetic tape of Examples 74 to 76 above were measured, and the results are shown in Table 14.

Claims (1)

[Claims] 1. A magnetic recording medium comprising a magnetic layer containing magnetic powder and a binder formed on a support, wherein the magnetic layer contains an organic dye compound having an acidic group or a salt thereof. A magnetic recording medium characterized by: 2. The magnetic layer contains an organic dye compound having at least one or more acidic groups selected from hydroxyl groups, carboxyl groups, sulfonic acid groups, and monovalent or divalent metal salts or amine salts thereof, or salts thereof. A magnetic recording medium according to claim 1.